`Solution` is a library to help you with working with ok/error-tuples by exposing special matching macros.
[](https://hex.pm/packages/solution)
[](https://travis-ci.org/Qqwy/elixir_solution)
[](http://inch-ci.org/github/qqwy/elixir_solution)
## Installation
You can install Solution by adding `solution` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:solution, "~> 0.1.0"}
]
end
```
## Examples
The following example snippets assume that you run
```elixir
require Solution
import Solution
```
(although of course, `Solution` is also fully usable without importing it.)
### Guards
`Solution` exposes three guard-safe functions: `is_ok(x)`, `is_error(x)` and `is_okerror(x)`
- `ok(x)` will match `:ok`, `{:ok, _}`, `{:ok, _, _}`, `{:ok, _, _, __}` and any longer tuple whose first element is `:ok`.
- `error(x)` will match `:error`, `:undefined` `{:error, _}`, `{:error, _, _}`, `{:error, _, _, __}` and any longer tuple whose first element is `:error`.
- `okerror(x)` matches both of these.
Solution also exposes versions of these that take a 'minimum-length' as second argument. A length of `0` works jus the same as above versions. Longer lengths only match tuples that have at least that many elements (as well as starting with the appropriate tag).
### SCase
`Solution.scase`works like a normal `case`-statement,
but will expand `ok()`, `error()` and `okerror()`macros to the left side of `->`.
```elixir
scase {:ok, 10} do
ok() -> "Yay!"
_ -> "Failure"
end
#=> "Yay!"
```
You can also pass arguments to `ok()`, `error()` or `okerror()` which will then be bound and available
to be used inside the case expression:
```elixir
scase {:ok, "foo", 42} do
ok(res, extra) ->
"result: \#{res}, extra: \#{extra}"
_ -> "Failure"
end
#=> "result: foo, extra: 42"
```
Note that for `ok()` and `error()`, the first argument will match the first element after the `:ok` or `:error` tag.
On the other hand, for `okerror()`, the first argument will match the tag `:ok` or `:error`.
### SWith
`Solution.swith` works like a normal `with`-statement,
but will expand `ok()`, `error()` and `okerror()` macros to the left side of `<-`.
```elixir
x = {:ok, 10}
y = {:ok, 33}
swith ok(res) <- x,
ok(res2) <- y do
"We have: \#{res} \#{res2}"
else
_ -> "Failure"
end
#=> "We have: 10 33"
```
You can also pass arguments to `ok()`, `error()` or `okerror()` which will then be bound and available
to be used inside the rest of the `swith`-expression:
```elixir
x = {:ok, 10}
y = {:error, 33}
z = {:ok, %{a: 42}}
swith ok(res) <- x,
error(res2) <- y,
okerror(tag, metamap) <- z,
%{a: val} = metamap do
"We have: \#{res} \#{res2} \#{tag} \#{val}"
else
_ -> "Failure"
end
#=> "We have: 10 33 ok 42"
```
Note that for `ok()` and `error()`, the first argument will match the first element after the `:ok` or `:error` tag.
On the other hand, for `okerror()`, the first argument will match the tag `:ok` or `:error`.
## Documentation
Full documentation can be found at [https://hexdocs.pm/solution](https://hexdocs.pm/solution).
## Changelog
- 0.1.0 - Initial version
